1. Field
The present disclosure relates to cutting of prefabricated concrete products. More precisely the present disclosure relates to a method and an apparatus for cutting cured slipform cast hollow-core concrete products with water jet cutting.
2. Description of Related Art
Prefabricated concrete elements, such as hollow-core slabs and solid concrete slabs, are conventionally cast by slipform casting on long casting beds as a continuous casting process. The length of said continuous casting process is defined either on the basis of the total length of the elements to be cast, or on the basis of the maximum length of the casting bed. The length of casting beds used in slipform casting can be up to 150-200 m, depending on the size of the element plant. When a slipform casting equipment has cast a continuous slab on a casting bed, the cast concrete mass is allowed to be cured on the casting bed. After the concrete mass has cured, the uniform cast element is cut, generally by sawing, into pieces with predetermined lengths on the basis of the design characteristics of the ready-made elements, and the cut concrete elements are lifted off the casting bed to storage, to wait for transportation to their appointed targets of usage.
Generally, concrete elements cast by slipform casting are prestressed, i.e., they are provided with reinforcing wires. Moreover, after slipform casting, the cast concrete elements can be provided with different apertures or cavities, for example for lead-ins or other required post-casting build-up of the elements. Apart from regular concrete mass, the casting material of slipform cast concrete elements can be, for example, fiber reinforced concrete mass.
For sawing cured concrete elements, there is usually employed a saw, or sawing equipment, with a diamond blade, because in hardness, cured concrete mass corresponds to rock material, and often it is also provided with reinforcing steel wires.
The sawing of a fresh, green element is also possible, but in that case the element to be sawed cannot contain reinforcing wires, or the sawing needs to be restricted in the areas not containing the reinforcing wires, because in a fresh element, the reinforcing wires would be detached from the cast element owing to their degree of prestressing, and this would lead to destructive results for the element.
Water jet cutting with abrasive water jet has also been experimented for cutting cured slipform cast products, but this is problematic for hollow-core slabs, since the hollow-core areas tends to break up the water jet and thus greatly decelerate the cutting process.